:root {
    --primary-color: #2c3e50;
    --secondary-color: #3498db;
    --success-color: #27ae60;
    --danger-color: #e74c3c;
    --warning-color: #f39c12;
    --light-bg: #f8f9fa;
    --border-color: #dee2e6;
    --text-color: #495057;
    --text-muted: #6c757d;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Helvetica Neue', Arial, sans-serif;
    background: url('/static/img/login-bg.jpg') center center / cover no-repeat;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    position: relative;
}

/* body::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(135deg, rgba(26, 38, 52, 0.8) 0%, rgba(44, 62, 80, 0.6) 50%, rgba(52, 73, 94, 0.8) 100%);
    pointer-events: none;
} */

.register-container {
    background-color: white;
    padding: 40px;
    border-radius: 16px;
    box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1), 0 8px 16px rgba(0, 0, 0, 0.06);
    width: 100%;
    max-width: 450px;
    position: relative;
    backdrop-filter: blur(10px);
    border: 1px solid rgba(255, 255, 255, 0.2);
    animation: fadeIn 0.5s ease;
}

.register-title {
    text-align: center;
    font-size: 28px;
    color: var(--primary-color);
    margin-bottom: 35px;
    font-weight: 600;
    position: relative;
}

.register-title::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 3px;
    background: linear-gradient(90deg, var(--secondary-color), var(--primary-color));
    border-radius: 2px;
}

.form-group {
    margin-bottom: 24px;
    position: relative;
}

.input-wrapper {
    position: relative;
    display: flex;
    align-items: center;
}

.input-icon {
    position: absolute;
    left: 16px;
    color: var(--text-muted);
    font-size: 16px;
    z-index: 2;
    transition: color 0.3s ease;
}

.form-group input {
    width: 100%;
    padding: 14px 16px 14px 48px;
    border: 2px solid var(--border-color);
    border-radius: 10px;
    font-size: 16px;
    color: var(--text-color);
    background-color: #fff;
    transition: all 0.3s ease;
    font-family: inherit;
}

.form-group input:focus {
    outline: none;
    border-color: var(--secondary-color);
    box-shadow: 0 0 0 3px rgba(52, 152, 219, 0.1);
    transform: translateY(-1px);
}

.form-group input:focus + .input-icon,
.input-wrapper:focus-within .input-icon {
    color: var(--secondary-color);
}

.form-group input::placeholder {
    color: var(--text-muted);
    transition: opacity 0.3s ease;
}

.form-group input:focus::placeholder {
    opacity: 0.7;
}

.form-group select {
    width: 100%;
    padding: 14px 16px 14px 48px;
    border: 2px solid var(--border-color);
    border-radius: 10px;
    font-size: 16px;
    color: var(--text-color);
    background-color: #fff;
    transition: all 0.3s ease;
    font-family: inherit;
    cursor: pointer;
    appearance: none;
    background-image: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="%236c757d" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><polyline points="6,9 12,15 18,9"></polyline></svg>');
    background-repeat: no-repeat;
    background-position: right 12px center;
    background-size: 16px;
    padding-right: 40px;
}

.form-group select:focus {
    outline: none;
    border-color: var(--secondary-color);
    box-shadow: 0 0 0 3px rgba(52, 152, 219, 0.1);
    transform: translateY(-1px);
}

.form-group select:focus + .input-icon,
.input-wrapper:focus-within .input-icon {
    color: var(--secondary-color);
}

.class-select select {
    width: 100%;
}


.btn-group {
    display: flex;
    gap: 12px;
    margin-top: 10px;
}

.btn {
    flex: 1;
    padding: 16px;
    border: none;
    border-radius: 10px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    text-transform: uppercase;
    letter-spacing: 0.5px;
    font-family: inherit;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
}

.submit-btn {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    color: white;
}

.submit-btn:hover {
    background: linear-gradient(135deg, #34495e 0%, #2980b9 100%);
}

.submit-btn:active {
    background: linear-gradient(135deg, #2c3e50 0%, #3498db 100%);
}

.back-btn {
    background: linear-gradient(135deg, var(--danger-color) 0%, #c0392b 100%);
    color: white;
}

.back-btn:hover {
    background: linear-gradient(135deg, #c0392b 0%, #a93226 100%);
}

.back-btn:active {
    background: linear-gradient(135deg, var(--danger-color) 0%, #c0392b 100%);
}

/* 动画效果 */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(10px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* 响应式设计 */
@media (max-width: 768px) {
    .register-container {
        margin: 20px;
        padding: 30px 25px;
        max-width: none;
    }

    .register-title {
        font-size: 24px;
        margin-bottom: 30px;
    }

    .form-group input,
    .form-group select {
        padding: 12px 14px;
        font-size: 15px;
    }

    .btn {
        padding: 14px;
        font-size: 15px;
    }

    .btn-group {
        gap: 10px;
    }
}

@media (max-width: 480px) {
    body {
        padding: 10px;
    }

    .register-container {
        margin: 10px;
        padding: 25px 20px;
    }

    .register-title {
        font-size: 22px;
    }

    .form-group {
        margin-bottom: 20px;
    }

    .btn-group {
        flex-direction: column;
        gap: 12px;
    }

    .btn {
        padding: 16px;
    }
}
